1. Field of the Invention
The present invention is related to alignment systems for inspecting or processing substrates used for production in the semiconductor industry. In particular, the invention relates to alignment systems for use with vision inspection systems or laser scribing systems and the like.
2. Brief Description of the Related Art
Robot manipulated substrates used for production in the semiconductor industry, including semiconductor wafers, flat panels, reticles, and the like, usually require accurate orientation and placement relative to a mark or indicator before a processing step can be applied. The steps of identifying initial substrate orientation and placement before aligning the substrate to a known position, called "profiling," consume a significant portion of the total substrate process time budget and impact the throughput of substrate material in the system. Typically during the substrate handling or aligning steps, the processing station remains inactive which equates to smaller yields and wasted resources.
To minimize the processing station idle time, robot-based substrate handlers traditionally utilize multiple end effector transport mechanisms and prealignment stations that mechanically center and profile substrate orientation marks for use in subsequent processing steps. Prealigning is a process of orienting and centering a substrate on the robot end effector so that an orientation mark, such as a flat or notch on the substrate surface, is set at a predefined angle and the substrate center is positioned at a predefined location on the end effector. Prealigning ensures that successively processed substrates are all oriented with the mark in the same direction and centered during the process. Prealigner-equipped systems typically use a robotic substrate handler which prealigns the end effector with respect to the substrate material, picks up the substrate material from a sourcing device, and then delivers the substrates to a process module for processing.
Processing a substrate exemplarily involves using a scribing system to mark the substrate surface in a desired location based upon the substrate profiling information. The substrates introduced into a process module are oriented and placed relative to the orientation and placement restrictions imposed by the equipment. The robotic substrate handler then moves to another sourcing device to retrieve a second substrate.
If the first substrate is improperly placed or misaligned, the design of these alignment systems requires the robotic substrate handler to traverse the processing station to recover the misplaced or misaligned substrate and attempt to correct the substrate's orientation or position problem in the process module. The robotic substrate handler will then re-traverse the processing station and return to the second substrate, still waiting in its sourcing device. This realignment process repeats until the first substrate is properly oriented and positioned in the process module. These physical alignment and orientation corrections may require significant time to complete and accordingly decrease the system throughput of substrate material.
Accordingly, it would be desirable to provide a multi-chamber, shared resource substrate processing system, whereby while one processing station performs the necessary orientation and placement for substrate profiling, a second processing station can prepare a second substrate for alignment and substrate profiling.